Vibration in 2009 Ford Escape, not tires or wheels

Maintenance/Repairs
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1


I have a highway-speed vibration in my 2009 Ford Escape AWD.



Here are the symptoms:



- feel the vibration at 85km/h and above (roughly 50 MPH and above).

- I feel the vibration on the seat, centre console (between seats) and especially in the seat headrest.

- no vibration on the wheel or pedals

- to see if it was engine-related, I took it up to 120km/h (75MPH) and then put it in neutral and let it coast. Vibration continues, and eventually goes away when speed gets below 80 or so.

- seems more noticeable on corners, but this may just be my perception of things



This is not related to tires or rims – I’ve swapped a brand new set of tires and rims to rule that out. I’m on the 3rd set of tires and still haven’t figured out this problem. Every guy I take this to, including the Ford dealer, immediately thinks “tires!” But even they’ve ruled it out now.



Car is still under warranty, but it’s been in the shop twice now, but they haven’t been able to find the source of the vibration.



Any ideas? Or other diagnostic tests that I can do to try and narrow down the cause? I want to fix this while I’m still covered by warranty!



Thanks!

2

Put the vehicle up on a lift and see if the vibration can be duplicated…If so, track it down! A bad drive-shaft, bad CV joint (there are lots of them in your AWD system…

3

Has anyone considered the possibility that the driveshaft may have lost a balancing weight or two?

An unbalanced drive shaft can cause these exact symptoms.
It is even possible that a bad u-joint on the driveshaft is to blame.

Edited to add:
It looks like Caddyman and I were typing at the same time, with similar thoughts!

4

Does the driveshaft still spin when in neutral?

Is there something I can do to confirm the drive shaft as the culprit?

5

Yes, it spins when you are in neutral and coasting on the highway.

If the vehicle is put on a chassis lift with the engine running and the trans in gear, and if someone in the cab gooses the accelerator, it should be visible when the driveshaft hits the right speed–if the driveshaft is the culprit.

6

Awesome thanks!

Will take it back and have them check that.